/Engine/Source/Runtime/CoreUObject/Public/UObject/Linker.h
Return the outermost resource package index of the resource pointed by LinkerIndex
the package index of the outermost
[FPackageIndex](API\Runtime\CoreUObject\UObject\FPackageIndex) ResourceGetOutermost ( [FPackageIndex](API\Runtime\CoreUObject\UObject\FPackageIndex) LinkerIndex ) const